Made a range trip to have the wife make a final decision on Berger 85.5 or the Hornady 90A-Tip and set scopes for a 600yd F-Open match this Saturday. Was an abnormally cool day (started at 80F, 84F when we finished).
For background, the shooter, my wife, shoots about 1.5MOA @ 600yds, shooting from a rest and bag.
Last 4 midrange scores of 559, 570, 565, 569.
The rifle is a kitchen assembled AR-15, 28", 1:7, 5R, 0.219"/0.224" shooting annealed twice/third fired 22 NosGar cases (weight sorted to a grain), CCI 450 (unsorted), SB6.5 powder (weighed to much better than +/- 0.1gr).
Charge for the 85.5 was 31.4gr, and a GUESS starting charge of 31.0gr for the 90A.
The 90As where seated deep , case length of 1.760", bullet length of 1.276", cartridge AOL 2.417".
The velocity started off low with a cold clean barrel. Even if you don't believe the accuracy of the Shotmarker it should show a trend. The 20 shots shown in the picture posted below were shot in the order 5 shots each 85.5/90A adjusted up 0.3 mils then 5 shots each 85.5/90A as listed in the picture.
For the 10 shots with the 85.5/31.4 load the ES=70, Avg=1977, SD=30.
For the ten shots with the 90A/31.0 load the ES=54, Avg=2051, SD=19
Later that morning Flo shot 10 more of the 85.5/31.4 load (no screen shots)
1989 2024 2025 2029 1980 1982 2007 2031 2020 1998 ES=40, Avg=2009, SD=19
Then 10 more of the 90A/31.0 load;
2040 2036 2004 2038 1998 2033 2050 2052 2032 1999 ES=54, Avg=2028, SD=20
All shot at a sort of typical F-Class slow fire pace.
On the previous range trip to test jump with the 90A, on a much warmer day,
S.D. of 30 shots (3 different seating depths) was 16, ES 55, mean 2059@ 600yds.
Avg velocity of all 50 shots with the 90A, two trips warm and cool day, was 2051fps@600yds.
No muzzle velocity measurements but backtracking with a calculator it's close to3000fps. 2940fps.
So, finally the question;
Why isn't the POI of the 90A-tip with a higher B.C. and loaded faster higher than the 85.5 @ 600yds?
I can get the 90A-tip load going faster than the 85.5 load, 31.0gr of powder was a guess and the A-tips are seated deeper into the case, but the higher B.C. and higher velocity doesn't make sense with POA/POI.
Maybe the groups are too big to really tell. The girl does pull a shot or two
For background, the shooter, my wife, shoots about 1.5MOA @ 600yds, shooting from a rest and bag.
Last 4 midrange scores of 559, 570, 565, 569.
The rifle is a kitchen assembled AR-15, 28", 1:7, 5R, 0.219"/0.224" shooting annealed twice/third fired 22 NosGar cases (weight sorted to a grain), CCI 450 (unsorted), SB6.5 powder (weighed to much better than +/- 0.1gr).
Charge for the 85.5 was 31.4gr, and a GUESS starting charge of 31.0gr for the 90A.
The 90As where seated deep , case length of 1.760", bullet length of 1.276", cartridge AOL 2.417".
The velocity started off low with a cold clean barrel. Even if you don't believe the accuracy of the Shotmarker it should show a trend. The 20 shots shown in the picture posted below were shot in the order 5 shots each 85.5/90A adjusted up 0.3 mils then 5 shots each 85.5/90A as listed in the picture.
For the 10 shots with the 85.5/31.4 load the ES=70, Avg=1977, SD=30.
For the ten shots with the 90A/31.0 load the ES=54, Avg=2051, SD=19
Later that morning Flo shot 10 more of the 85.5/31.4 load (no screen shots)
1989 2024 2025 2029 1980 1982 2007 2031 2020 1998 ES=40, Avg=2009, SD=19
Then 10 more of the 90A/31.0 load;
2040 2036 2004 2038 1998 2033 2050 2052 2032 1999 ES=54, Avg=2028, SD=20
All shot at a sort of typical F-Class slow fire pace.
On the previous range trip to test jump with the 90A, on a much warmer day,
S.D. of 30 shots (3 different seating depths) was 16, ES 55, mean 2059@ 600yds.
Avg velocity of all 50 shots with the 90A, two trips warm and cool day, was 2051fps@600yds.
No muzzle velocity measurements but backtracking with a calculator it's close to
So, finally the question;
Why isn't the POI of the 90A-tip with a higher B.C. and loaded faster higher than the 85.5 @ 600yds?
I can get the 90A-tip load going faster than the 85.5 load, 31.0gr of powder was a guess and the A-tips are seated deeper into the case, but the higher B.C. and higher velocity doesn't make sense with POA/POI.
Maybe the groups are too big to really tell. The girl does pull a shot or two
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